In machining operations, considerable success has been experienced in the recent past by use of the so-called "high-temperature" materials. Such materials (which include ceramics and carbides) are very hard and permit high metal removal rates, particularly in cutting operations. However, in addition to being hard, these materials are also brittle, and it has been found that the life of tools formed from such materials is shortened by the appearance of cracks on the surface, which cracks enlarge and, eventually, lead to total destruction by breakage of the tool. When one attempts to avoid such cracking breakage of the tool. When one attempts to avoid such cracking by operating at a lower metal removal rate, the advantages of using such materials in the first place disappear, since other materials which are not subject to cracking can be used at such lower metal removal rates. Furthermore, there are many materials which (like the tool) have high-temperature characteristics and which can be machined only by ceramic and carbide tools. In machining such metals, the cracking appears even at lower rates. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a machine tool which can operate at high metal removal rates and still enjoy a long life of service.
Another object of this invention is the provision of a machine tool including means for preventing cracking in a high-temperature tool.
A further object of the present invention is the provision of a machine tool having means for prolonging the life of a ceramic or carbide tool.
It is another object of the instant invention to provide a machine tool having means for maintaining a high-temperature tool at a constant temperature despite changes of stress in the tool.
A still further object of the invention is the provision of a machine tool having a long life despite respected changes in metal removal rates.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.